A quick and rough Tutorial, how to record a Midi-track played
in Rosegarden to an Audio-track in Rosegarden using QSynth (a GUI for Fluidsynth).

1. First start jackd (I recommend to use qjackctl for doing that. You can see the created connections there too.)
2. Start QSynth (in the options, select jack as audio driver/output). Load a SoundFont(TM Creative Technologies Ldt.).

3. Start Rosegarden

4. In RG, in the device manager create a new device, name it QSYNTH and connect it to QSynth
(the entry is called somehow like "131:0 snyth input port (qsynth:0) (write)")

5. Select a MIDI track. In the playback parameter panel choose the QSYNTH device as output.
Further select instrument, channel and program for the track using the QSYNTH device.

6. For a testing purpose, you can playback the midi track now. You should hear it.

10. Press the record button in the Rosegarden transport panel.
The playback starts and the midi track is being recorded to the audio track.
(Note: If you de-connected QSynth from system-playback, you may not hear anything now)